Is Your Air Filter Affecting Your Indoor Air Quality?

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Your air filter does more than provide a layer of protection for the HVAC system. It also plays an essential role in your home’s indoor air quality (IAQ). Use the wrong size or type of filter, and you could inadvertent make yourself and others sick. But if you’re not sure whether your current filter is helping or hurting, contact Bloomington Heating & Air to have our technicians evaluate your HVAC system and design a custom IAQ solution!

What Happens If I’m Using The Wrong Air Filter?

It might not sound like a big deal, but using the wrong air filter can lead to health concerns and costly HVAC repairs. An air filter that’s too large won’t be able to trap allergens but will instead allow them into the air. Conversely, when a filter’s fibers are woven too tightly, they can impede proper airflow, which puts a strain on the unit and may lead to a breakdown.

What Type Of Air Filter Should I Use?

Air filters are sold in stores and online. But no matter where you purchase one, it’s important to make sure the type matches the needs of your household and HVAC system. All filters act as sieves for pollutants that come from a variety of indoor and outdoor sources, including coal, gas, oil, and other fuels, household cleaning products, and building materials such as damp or wet carpet, insulation, or pressed wood products.

When you’re choosing a filter, make sure to check the minimum efficiency reporting value (MERV). This rating is given based on a filter’s ability to trap airborne particles and ranges from 1 to 16 — a higher number signifies better filtration. To improve your home’s IAQ, we recommend using a filter with a MERV rating between 9 and 12. Additionally, it’s essential to choose the type of filter that fits your needs. Here are the most popular options.

Disposable Pleated

Polyester pulls small particles, such as dust mites, from the air, but a disposable pleated filter needs to be changed frequently.

High-Efficiency Pleated

Several inches of synthetic cotton attaches to a rigid metal grid and stops the pleats from fluttering or leaking.

Permanent Electrostatic

This washable filter has self-charging cotton fibers and can be reused permanently.

Disposable Electrostatic

Electrostatic cotton fibers gather polluting particles as they attempt to blow from the HVAC system. This type of filter is suitable for homes with kids, pets, or smokers.

Disposable Fiberglass

Perhaps the most common type, a disposable fiberglass filter is good for people without respiratory issues, as these filters aren’t the best at improving the IAQ.

Why Is My Air Filter Black?

Any air filter will change color as it strains out dirt and dust. If your filter is turning black, this discoloration likely has one of three causes.


Black coloration is a common sign of soot, a byproduct of burning candles. But if you love the ambiance created by candles, don’t despair — just trim the wicks back to ¼ inch before each lighting. Another option is to use all-natural candles, such as soy-based, which produce less soot when burned.

Particle Build-Up

If it’s been ages since you’ve changed furnace filters, any black coloration is likely the result of a substantial buildup of dirt, dust, and other particle debris. Changing the filter every month to three months is the best way to avoid this situation.


When your home air conditioner runs, it produces condensation due to the cooling process. While this moisture generally drains out of the home and system, sometimes it transfers to the air filter, laying the foundation for mold growth.

Mold can appear in a variety of colors, but if you notice any on the air filter, immediately throw it away and install a new one. Then call Bloomington Heating & Air to schedule an appointment, as untreated mold can increase the risk of respiratory issues, such as asthma and sinusitis.

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